I need to know for a science project and i cant find anywhere, where it says how it was formed
Ground water is not formed by itself. Ground water is actually rain water which seeped or infiltrate into ground and reach until an underground reservoir. This is also call aquifer. However rain or precipitation is not the only source of recharge for ground water. It can also be recharged through water infiltrated by lakes and rivers.
How is groundwater formed?
Answer: When water percolates down through the soil